Vehicle lift apparatus



July 14, 1964 Filed Sept. 24, 1962 Fig- 2 Sheets-Sheet l 55 Inventors e Jessa E. CLARKE DUDLEY $.CLARKE Gama 7 lr/ncvr July 14, 1964 J CLARKE ETAL 3,140,641

VEHICLE LIFT APPARATUS Filed Sept. 24,- 1962 I 2 Sheets-Sheet 2 Z i A 47 45 24 Q Fig.4 I" g 44 g 2 48 g 48 I g 2 a 53 5 46 o 50 w v &\\\\\ 23 Inverztors JESSE E. CLARKE DUDLEY S. CLARKE 9% FM &

United States Patent 3,140,641 VEHICLE LIFT APPARATUS Jesse E. Clarke, Hinsdale, and Dudley S. Clarke, Chicago, Ill., assignors to Autoquip Corporation, Chicago, Ill., a corporation of Illinois Filed Sept. 24, 1962, Ser. No. 225,659 14 Claims. (Cl. 914) The present invention relates to a vehicle lift apparatus or the like incorporating a valve for controlling the length of the ram stroke and for low oil level control.

The present application is a continuation-in-part of our pending application Serial No. 101,903, filed April 10, 1961.

The majority of the permanently installed vehicle lifts, such as those used in garages, service stations, etc., are of a type commonly designated self-contained, semihydraulic or pneumatic-hydraulic. A portion of the hydraulic cylinder and ram is filled with oil. When the ram is to be raised, air is injected into the interior of the ram above the level of the oil. The pressure of the air displaces the oil in the ram, forcing that oil from the interior of the ram through an orifice in the ram into the cylinder per se. The rate at which the ram moves upwardly under a given air pressure supply is controlled by the rate at which the oil from the interior of the ram will flow through the orifice into the cylinder.

Should the level of the oil in the apparatus become low, so that all of the oil in the ram is displaced from the interior of the ram before the ram reaches the upward extent of its stroke, the result will be that air will commeuce flowing through the orifice into the portion of the cylinder below the ram. Since the air will move through the orifice much more rapidly than will the oil, the result will be a sudden pressurizing of the portion of the cylinder behind or below the ram. This will cause the ram to move upwardly at an unduly high rate of speed. The unfortunate result of such a situation usually is, at the very least, damage to the ram. If a car is on the lift, the car actually may be pitched from the lift. In instances in which such a situation has occurred with no vehicle on the lift, the ram actually has been shot out of the cylinder like a projectile from a gun, damaging the building in which the lift was located and endangering those in the vicinity. Even when some such disasterous results does not occur, the air entering the cylinder will not re turn to the interior of the ram when the lift is lowered. The lift then does not move smoothly, but in dangerous jerks.

As a protection measure, lift manufacturers generally utilize some sort of a low oil level control. In some in stances such'controls take the form of a float-actuated valve, much like the float valve in a toilet tank. Other manufacturers have utilized a caged float inside the ram, which float would be lowered to block an orifice (olfset from the air tube) as the bottom of the ram approached the surface of the oil within the ram. In the latter devices, it is necessary, in order to make the device effective, to provide a fluid seal, i.e. a packing gland or the like, about the air supply tube at the point at which it passes through the bottom of the ram. A carefully machined valve seat is required in the ram. When that seat and/ or valve closure member on the float wears, the valve will leak and the ram will creep above its desired height.

We have devised a novel form of low oil level control apparatus which utilizes a float having means thereon to cover the opening in the bottom of the ram through which the air supply line passes. The opening in the bottom of the ram about the air supply line thus serves as the control orifice to regulate the speed of ram movement. When a low oil condition is encountered, or if the ram is to be stopped at a particular level by our regulating valve, as

3,140,641 Patented July 14., 1964 hereinafter described, the float is brought into contact with the bottom of the ram surrounding the control orifice. The structure of our apparatus is such that when such a contact is made, a seal is provided both between the float and the bottom of the ram, and between the float and the exterior of the air supply tube, thus effectively sealing the orifice.

The device of our invention is exceedingly simple inexpensive to manufacture. The float utilizes the air supply tube as a guide, thus eliminating any necessity for cages or the like used with many of the prior art devices. N0 packing gland is needed betwen the ram and the air supply tube. The contact of the float with the ram is cushioned so that there is no battering of the float when contact with the ram is made, which often resulted in damage to other types of devices. As the ram is raised and lowered, there are no frictionally contacting surfaces to wear, such as, for example, the wear that occurs in a packing gland or the wear in a mechanical valve as a float moves up and down with the change in oil level.

One of the important advantages of our invention is the ease with which it may be installed and adjusted when a lift is manufactured. Furthermore, should field repairs or adjustments be necessary, these can be made easily and simply. In order to make them, there is no necessity for removing the ram from its cylinder, or for dismantling the ram. In prior art devices, which had significantly more wear than does the apparatus of our invention, substantial dismantling of the lift structure was necessary in order to obtain access to the parts which were to be repaired or replaced. The valve of our invention may be installed on most pneumatic-hydraulic lifts not already equipped with low oil control devices.

A further important advantage of our invention is that, without any special equipment or devices, the extent of the ram stroke, i.e. the distance that the lift is raised above the floor, may be set at any desired point within the maximum stroke of the ram. For example, in some instances the purchaser of a lift will intend to install it in a location at which the present clearance heights will restrict the extent to which a vehicle can be lifted. However, the purchaser intends, at some time in the future, to remodel the building and provide additional vertical clearances. He wishes to purchase a lift which, when it is first installed, will only travel a part of its maximum travel, but which, after modification of the building, can be used to raise a car to a greater height. Under present commercial practices, for the payment of an additional fee a purchaser can acquire a so-called two stroke lift which is capable of field adjustment to obtain the desired results.

The apparatus of our invention can achieve the same results without any structural modification whatsoever. When it is first installed, the apparatus can be so adjusted that the float valve will rise only to a limited extent within the ram housing. As the bottom of the ram reaches the float, the orifice in the bottom of the ram is closed, stopping the movement of the rain at that point. If it is subsequently desired to have a greater lift distance, the extent to which the float will rise within the ram housing is increased, thus allowing the ram to extend farther out of the cylinder before the orifice is closed to stop the ram movement.

Further objects and advantages will become apparent from the following description taken in conjunction with the drawings, in which:

FIGURE 1 is a vertical section of a hydraulic cylinder and ram (somewhat diagrammatic) illustrating an embodiment of our invention therein;

FIGURE 2 is a partial section as viewed along line 22 of FIGURE 1 illustrating the float valve in its and I 3 position just prior to the closing of the orifice in the bottom of the ram;

FIGURE 3 is a view similar to FIGURE 2 of an alternative embodiment; and

FIGURE 4 corresponds to FIGURE 3 but shows the sealing action of this embodiment.

FIGURE 1 illustrates a hydraulic cylinder generally 10 within which is received a ram generally 11. The details of such a structure are familar to those skilled in the art. In general, cylinder 10 includes a cylindrical body 12 with a base 13 closing the bottom end thereof. A mounting flange 14 is provided at the top of the body. Annular bearings 16 are secured to the inner wall of cylinder 10 to support the ram 11 therein. A packing ring 17 is positioned between the cylinder 1% and the ram 11 above the top bearing 16.

Ram 11 includes a cylindrical body 7.8 having a head 19 secured in the top end thereof and a bottom 2 secured in the lower end. Head has a threaded opening into which is threaded a fill plug 22. Bottom has an opening 23 extending therethrough.

An air supply tube or pipe 24 extends vertically through the hollow interior of cylinder 10, opening 23 and the hollow interior of ram 11. Pipe 24 is fixed to cylinder 10 and has a pipe coupling 25 secured to the lower end thereof. The upper end of pipe 24 opens into the hollow interior of ram 11. Means (not shown) is connected to coupling 25 to supply air to tube 2 to raise ram 11 with respect to cylinder 10, or to release air through pipe 24 to allow ram 11 to lower into cylinder 10. Pipe 24 fills part, but not all, of opening 23. The remaining, unfilled, portion of opening 23 serves as an orifice for the flow of oil between the interior of ram 11 and cylinder 10.

An oil antispray baflle 27 is mounted on pipe 24. In normal operation, it is fixed in position on pipe 24 but is so constructed that it may be moved upwardly or downwardly along pipe 24, should that be desired. To achieve this purpose, we form bafl le 27 from a deformable synthetic rubber having sumcient rigidity to normally main tain its shape. An ideally suitable material for this purpose is a chloroprene rubber, such as that sold under the trademarks Neoprene or Duprene. Baflie 27 has a central opening 28 through which pipe 24 extends. Opening 28 is made sufliciently small so that the baflie 27 will frictionally engage pipe 24.

Surrounding pipe 24 below baflle 27 and above bottom 20 is a float 30. We prefer to form float 30 of wood, such as spruce, yellow poplar, white cedar, northern white pine or western red cedar. It also may be molded from a plastic or a closed air cell sponge plastic. The material from which float 30 is formed should have a specific gravity of about 0.6 or less.

Float 30 is of generally cylindrical configuration and has an axial opening 31 extending therethrough to receive tube 24. The diameter of opening 31 should be slightly larger than the external diameter of tube For example, in an embodiment in which tube 24 has an external diameter of 0.675, the diameter of opening 31 is ff of an inch. Extending about the bottom corner of the float is a groove 32 in which is seated an O-ring 33. O-ring 33 is suitably secured to float 30, as by means of an adhesive. The adhesive should be of a type that will not be alfected by the liquids, e.g. oil, present. A suitable adhesive for this purpose is that sold under the trademark Eastman 910. The internal diameter of G-ring 33 should be larger than the diameter of opening 23 in bottom 20, so that when the O-ring contacts the bottom a fluid seal will be formed between the float and bottom outside of opening 23.

The interior of the float 30 defines an annular groove generally 35 about opening 31. The upper portion 36 of groove 35 is generally cylindrical in configuration, while the lower part 37 of groove 35 has the shape of a frustum of a cone. The angle of taper of the lower part 37 should be between about 50 and about 60 as measured from the vertical axis of opening 31. Some minor variation in this angle of taper is permissible, but for best results the specified range should be observed. If too small an angle is used, substantially less than 50, the O-ring 38 (hereinafter described) will be pulled against tube 24 by friction. It the angle is too flat, substantially greater than 60, the desired sealing by O-ring 38 will be difiicult to obtain because the O-ring will not be wedged against tube 24 as desired.

O-ring 38 is received about tube 24 within groove 35. The internal diameter of O-ring 38 should be larger than the external diameter of tube 24, so that normally no contact between the two will result as float 30 moves up and down along tube 24. In an embodiment in which pipe 24 has an external diameter of 0.675 inch, the internal diameter of O-ring 38 is 0.687 inch. If the O-ring is so small that contact is made, in normal use wear will occur to enlarge the internal diameter thereof to about the specified size. Four radial holes 39 extend through float 30. Holes 39 are positioned so that their axes lie approximately at the top of groove 35. The holes 39, groove 35 and the portion of opening 31 below groove 35 and between float and tube 24 form a passageway for the flow of oil to orifice 23 after O-ring 33 has seated against bottom 20. Because of the relative size of the various portions of this passageway, the flow of oil therethrough will have a substantial increase in velocity and will provide a pressure drop about O-ring 38. This will cause O-ring 36 to move downwardly against the wedging faces of portion 37 therein, and the O-ring will be compressed between those wedging faces of float 30 and pipe 24 to result in an obstruction of the passageway and preventing any further flow of oil therethrough. O-rings 33 and 38 should be made of a synthetic rubber of a general type such as that described for baffle 27.

Without dismantling the lift structure, access may be had to the valve by removing fill plug 22. An elongated tool having a plurality of hooks on the bottom end thereof may be inserted through the opening in top 19, the hooks engaged under the downwardly extending flange of baffle 27 and the bafile pulled upwardly. Baflle 27 may be rolled or otherwise deformed to allow it to pass through the opening in the top of the ram. Similarly, float 30 may be lifted out of the opening in the top of the ram, since the external diameter of the float is smaller than the diameter of the opening in top 19. These operations are reversed to replace the parts. Float 30 is lowered through the top opening and allowed to slide down over the top of pipe 24. Baflle 27 is inserted through the top opening, and slipped over the top of pipe 24. A piece of pipe having an internal diameter larger than the external diameter of pipe 24 is inserted through the top opening, and pushed down against the top of baffle 27 until bafile 27 has been lowered to its desired position on pipe 24.

In normal use, float 30 would rest against the under side of baffle 27, as illustrated in FIGURE 1. When air is injected into the interior of ram 11 through pipe 24, that air displaces the oil from the interior of the ram with the oil passing out through the orifice formed by opening 23 and into the interior of the cylinder 10. This displacement of oil causes ram 11 to move upwardly, with the rate of movement being controlled by the rate of flow of oil through the orifice in bottom 20. When the bottom 20 passes beyond the position illustrated in FIGURE 2 and contacts O-ring 33, the flow of oil about the outside of float 30 to opening 23 is obstructed, so that thereafter oil can only flow through the passageway formed by openings 39, groove 35 and opening 31. This flow of oil through the internal passageway in float 30 causes O-ring 38 to move down into the lower part 37 of groove 35, where the O-ring is wedged between the float and tube At this time, the flow of oil to the orifice formed by opening 23 is fully obstructed so that the ram will stop in that position. The seal is so effective that even after many hours the ram will not have moved from the position at which it originally stopped.

When the lift is to be lowered, air is released through pipe 24, allowing the oil to flow from below ram 11 through opening 23 and into the interior of ram 11. O- ring 38 immediately returns to the position illustrated in FIGURE 2, and the ram 11 moves downwardly away from float 30.

Should a low oil condition occur, float 30 will ride at the surface of the oil with the bottom portion of the float submerged. The float should have sufficient weight so that the surface of the oil will be above the top of openings 39. As the ram is raised and contacts the float, the same sealing action previously described will occur. First, a seal will be obtained by the contact of O-ring 33 With the face of bottom 20 of the ram. Thereafter, 0- ring 38 will move down to seal between the float and the pipe 24. Thus, the ram never will move to a level at which air will pass through opening 23.

FIGURES 3 and 4 represent an alternative embodiment utilizing a plastic float generally 45 having a body 44 and a synthetic rubber skirt 46 in the form of a bellows. The plastic from which the main body 44 of the float is formed may be any suitable plastic which will float on, and will not be deleteriously affected by, the hydraulic fluid used in the cylinder and ram. We have found a micro-balloon epoxy resin to be eminently suited for this purpose. For the skirt 46, we have used a Buna-N synthetic rubber.

Float body 44 has an axial opening 47 to enable it to fit about air tube 24 and to move easily up and down the air tube. For example, with an air tube of inch external diameter, the diameter of internal opening 47 is 7 inch. Four oil path holes 48 are provided between the exterior of the body and the central opening 47 therein. Holes 48 are at a height such that they are below the surface of the hydraulic fluid when float 45 is floating therein. In other words they are in the portion of the float that will be submerged.

Skirt 46 is suitably secured to the body 44 as by means of an adhesive. To facilitate locking them together, the top of the skirt is provided with an annular projection 49 which is received in a corresponding groove in the bottom of the body. It will be noted that the aflixation of the skirt 46 to the main body of the float 45 fixes the size of the upper end of the skirt. In other words, by means of the affixation of the skirt to the main body of the float, the upper portion of the skirt (that part at, and adjacent to projection 4) cannot move radially with respect to the axis of the float (represented in the drawings by tube 24). To prevent outward radial displacement of the bottom of the skirt, a metal ring 50 is embedded therein.

Skirt 46 has the shape of a solid of revolution-that is the plane figure of the cross sectional views revolved about the axis represented by tube 24. There is an inner annular projection 52. The normal internal diameter of projection 52 is only slightly larger than the external diameter of tube 24, e.g. ,4, of an inch larger. Externally there is an annular recess 53 which under normal conditions has an apex at a slightly higher elevation than is projection 52.

Float 45 of FIGURE 3 is installed in the ram 11 in the same manner as previously described with respect to float 30 of FIGURES 1 and 2. When air is injected into ram 11 through pipe 24 to raise the ram in the cylinder, the oil then within the ram is forced from the ram into the cylinder through opening 23. At this stage of course, float 45 is supported by the hydraulic fluid and is spaced from the base 20 of ram 11 as illustrated in FIGURE 3. As the base 20 of the ram approaches the float (either by reason of the float being held down by baflie 27 or by reason of low oil condition in the ram) the skirt 46 will seat against the bottom 20 of the ram.

As illustrated in FIGURE 4, the bottom annular rim 54 of the skirt contacts bottom 20 of the ram and forms an oil seal about opening 23 in the ram. With a seal being thus formed and with the continued injection of air into the ram through pipe 24, the only path remaining for the flow of oil from the ram to the cylinder is through holes 48, central opening 47, through inner projection 52 and through opening 23. This path for the flow of oil is sufficiently restricted so that the hydraulic fluid will not flow therethrough at a rate suflicient to equalize the pressure in the cylinder (below ram 11) with the pressure being created within ram 11.

Thus there will be a pressure differential applied to skirt 46. Externally thereof is the relatively high pressure of the interior of the ram. On the interior of the skirt, particularly on the portion below projection 52 is a relatively lower pressure commensurate with the lower pressure of the interior of the cylinder proper. This pressure differential causes skirt 46 to collapse with projection 52 moving into contact with the exterior of tube 24, as illustrated in FIGURE 4. The top and bottom of the skirt 46 are restrained against outward expansion. Therefore the movement of the skirt is one in which the angular sides of recess 53 close (the angle therebetween is sharpened), the distance between bottom rim 54 and the top of the skirt diminishes, and inner annular projection 52 moves inwardly to form a fluid tight seal about tube 24.

This seal is remarkably effective. Any pressure differential suflicient to elevate ram 11 in cylinder (e.g. 3 /2 pounds per square inch or more) will compress skirt 46 and stop the flow of hydraulic fluid from the interior of the ram to the cylinder. Of course, as soon as air is released from the ram through tube 24, the pressure differential on the skirt will be relieved and the skirt will return to the configuration illustrated in FIGURE 3.

The foregoing description of a specific embodiment is for the purpose of complying with 35 U.S.C. 112, and should not be construed as imposing unnecessary limitations upon the appended claims inasmuch as modifications and variations thereof will be apparent to those skilled in the art.

We claim:

1. A lift for a vehicle or the like comprising: a hydraulic cylinder having its axis generally vertical and adapted to contain a quantity of hydraulic fluid; a hollow hydraulic ram in said cylinder, said ram having an opening in the bottom thereof; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of said ram above the normal level of hydraulic fluid therein, said tube being smaller than said opening to define an orifice thereabout; a float inside said ram, surrounding said tube and movable vertically with respect to said tube, said float having means on the bottom thereof to form a fluid seal between the float and the bottom of said ram about said orifice when said float and bottom are in juxtaposition, said float being buoyant with respect to said hydraulic fluid; means between said float and tube to form a seal therebetween when said float and bottom are in juxtaposition; and means to limit the extent of upward movement of the float with respect to the tube, the last means being vertically adjustable whereby the height to which the float will rise may be varied.

2. A lift for a vehicle or the like comprising: a hydraulic cylinder having its axis generally vertical and adapted 'to contain a quantity of hydraulic fluid; a hollow hydraulic ram in said cylinder, said ram having an opening in the bottom thereof; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of said ram above the normal level of hydraulic fluid therein, said tube being smaller than said opening to define an orifice thereabout; a float inside said ram, surrounding said tube and movable vertically with respect to said tube, said float having means in the bottom thereof to form a fluid seal between the float and the bottom of said ram about said opening when said float and bottom are in juxtaposition, said float having a normally open internal passageway between the bottom of the float, about said tube and extending to the outside of the float, said float being buoyant with respect to said hydraulic fluid; means between said float and said tube to close said passageway in response to the rapid flow of fluid through said passageway when said fluid seal has been effected between the float and the bottom of said ram; and means to limit the extent of upward movement of the float with respect to the tube.

3. A lift for a vehicle or the like comprising: a hydraulic cylinder having its axis generally vertical and adapted to contain a quantity of hydraulic fluid; a hollow hydraulic ram in said cylinder, said ram having an opening in the bottom thereof; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of said ram above the normal level of hydraulic fluid therein, said tube being smaller than said opening to define an orifice thereabout; a float having an axial opening therethrough slightly larger than the external diameter of said tube, said float being positioned inside said ram with the tube extending through said axial opening, said float having an annular groove surrounding said opening and concentric therewith, the top portion of said groove being substantially larger than said opening, the bottom portion of said groove tapering downwardly and inwardly to said opening, said float having means in the bottom thereof to form a fluid seal between the float and the bottom of said ram about said opening when said float and bottom are in juxtaposition, said float being buoyant with respect to said hydraulic fluid; an O-ring in said groove, said O-ring having a central opening sufficiently larger than the external diameter of said tube that there is no contact between said O-ring and tube when said O-ring is in the top portion of the groove and when said O-ring is in the bottom portion a fluid seal will be effected between said tube and said float; and means to limit the extent of upward movement of the float with respect to the tube.

4. A lift for a vehicle or the like comprising: a hydraulic cylinder having its axis generally vertical and adapted to contain a quantity of hydraulic fluid; a hollow hydraulic ram in said cylinder, said ram having an opening in the bottom thereof; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of said ram above the normal level of hydraulic fluid therein, said tube being smaller than said opening to define an orifice thereabout; a float inside said ram, surrounding said tube and movable vertically with respect to said tube, said float having means in the bottom thereof to form a fluid seal between the float and the bottom of said ram about said orifice when said float and bottom are in juxtaposition, said float having an internal passageway between the bottom of the float, about said tube and extending to the outside of the float, said float being buoyant with respect to said hydraulic fluid; means between said float and said tube to close said passageway in response to the rapid flow of fluid through said passageway when said fluid seal has been effected between the float and the bottom of said ram; an antispray baflle positioned above said float, surrounding said tube and frictionally engaging said tube, said baflie being formed of a deformable synthetic rubber having suflicient rigidity to normally maintain its shape.

5. A lift for a vehicle or the like comprising: a hydraulic cylinder having its axis generally vertical and adapted to contain a quantity of hydraulic fluid; a hollow hydraulic ram in said cylinder, said ram having an opening in the bottom thereof; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of said ram above the normal level of hydraulic fluid therein, said tube being smaller than said opening to define an orifice thereabout; a float having an axial opening therethrough slightly larger than the external diameter of said tube, said float being positioned inside said ram with the tube extending through said axial opening, said float having an annular groove surrounding said opening and concentric therewith, the top portion of said groove being substantially larger than said opening, the bottom portion of said groove tapering downwardly and inwardly to said opening, said float being buoyant on said hydraulic fluid; an O-ring in said groove, said O-ring having a central opening sufliciently larger than the external diameter of said tube that there is no contact between said O-ring and tube When said O-ring is in the top portion of the groove and when said O-ring is in the bottom portion a fluid seal will be effected between said tube and said float; a second O-ring secured to said float and extending downwardly from the bottom of said float, said second O-ring being positioned to surround said tube and having a diameter larger than the size of the opening in the bottom of the ram; an antispray baffle positioned above said float, surrounding said tube and frictionally engaging said tube, said baflle being formed of a deformable synthetic rubber having suflicient rigidity to normally maintain its shape.

6. A valve apparatus for a vehicle lift or the like having a hollow hydraulic ram mounted in a hydraulic cylinder adapted to contain a quantity of hydraulic oil and with a cylindrical air tube extending from the cylinder vertically upwardly through an opening in the bottom of the ram and terminating in the interior of the ram above the normal level of oil therein, said apparatus comprising: a float formed of a solid material having a speciflc gravity of no greater than about 0.6, said float having an axial opening therethrough of a diameter only slightly larger than the external diameter of said tube whereby said float may he slipped over said tube in the ram with the tube through the opening in the float, said float having an annular groove surrounding said opening and concentric therewith, the top portion of said groove being substantially larger than said opening, the bottom portion of said groove tapering downwardly and inwardly to said opening, said float having means on the bottom thereof to form a fluid seal between the float and the bottom of said ram about said opening when said float and bottom are in juxtaposition; an O-ring in said groove, said O-ring having a central opening sufliciently larger than the external diameter of said tube that there is no contact between said O-ring and tube when said O-ring is in the top portion of the groove and when said O-ring is in the bottom portion a fluid seal will be effected between said tube and said float; and means to limit the extent of upward movement of the float with respect to the tube.

7. A valve apparatus for a vehicle lift or the like having a hollow hydraulic ram mounted in a hydraulic cylinder adapted to contain a quantity of hydraulic fluid and with a cylindrical air tube extending from the cylinder vertically upwardly through an opening in the bottom of the ram and terminating in the interior of the ram above the normal level of hydraulic fluid therein, said apparatus comprising: a float having an axial opening therethrough of a diameter only slightly larger than the external diameter of said tube whereby said float may be slipped over said tube in the ram with the tube through the opening in the float, said float having an annular groove surrounding said opening and concentric therewith, the top portion of said groove being substantially larger than said opening, the bottom portion of said groove tapering downwardly and inwardly to said opening, said float being buoyant with respect to said fluid; an O-ring in said groove, said O-ring having a central opening sufficiently larger than the external diameter of said tube that there is no contact between said O-ring and tube when said O-ring is in the top portion of the groove and when said O-ring is in the bottom portion a fluid seal will be effected between said tube and said float; a second O-ring secured to said float and extending downwardly from the bottom of said float, said second O-ring being positioned to surround said tube and having a di- 9 ameter larger than the size of the opening in the bottom of the ram; an antispray baflie frictionally positioned above said float, surrounding said tube and frictionally engaging said tube, said baflle being formed of a deformable synthetic rubber having suflicient rigidity to normally maintain its shape.

8. A device for forming a fluid seal between a cylindrical member and a second member having a cylindrical opening therethrough through which opening said cylindrical member extends, when the flow of fluid between said members in a given direction exceeds a predetermined velocity, said device comprising: an annular groove in said second member with its axis concentric with the axis of said opening, the portion of said groove at the upstream end with respect to said direction of flow being substantially larger than said opening, the part of said groove from said portion tapering away from said portion and toward said opening; and an O-ring in said groove, said O-ring having a central opening sufficiently larger than the diameter of said cylindrical member that there normally is no contact between the O-ring and the cylindrical member when said O-ring is in said portion of said groove, and when said velocity is exceeded said O-ring will be urged into said part of said groove to contact both the taper of said second member and said cylindrical member to form a fluid seal therebetween.

9. A lift for a vehicle or the like comprising: a hydraulic cylinder adapted to contain a quantity of hydraulic fluid and having its axis generally vertical; a hollow hydraulic ram in said cylinder, said ram having an opening in the bottom thereof; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of said ram above the normal level of said hydraulic fluid therein, said tube being smaller than said opening to define an orifice thereabout; and a float inside said ram, surrounding said tube, buoyant with respect to said hydraulic fluid and movable vertically with respect to said tube, said float having means in the bottom thereof to form a fluid seal between the float and the bottom of said ram about said opening when said float and bottom are in juxtaposition, said float having a normally open internal passageway between the bottom of the float, about said tube and extending to the outside of the float, whereby, when said float seats against the bottom of the ram and a seal results, the injection of additional air into the ram through the tube will result in a pressure differential between the interior of the ram and said cylinder, said float having movable means to close said internal passageway in response to the occurrence of said pressure differential.

10. A lift for a vehicle or the like comprising: a hydraulic cylinder adapted to contain a quantity of hydraulic fluid and having its axis generally vertical; a hollow hydraulic ram in said cylinder, said ram having a bottom member with an opening therein; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of the ram above the normal level of hydraulic fluid therein, said tube being smaller than said opening whereby when air is injected into said ram through said tube, hydraulic fluid will be forced from the interior of the ram through the portion of the opening between the bottom member and tube and into the cylinder to raise the ram; a float member inside the ram, surrounding the tube, buoyant on said hydraulic fluid and movable vertically with respect to the tube, whereby the float member will normally, unless otherwise restrained, assume a position at the surface of the hydraulic fluid in the ram with a portion of the float member below the surface of the hydraulic fluid, said float member having an opening in said portion from the exterior thereof to the part of the float member about the tube adjacent the bottom of the float member; means between said members to form a seal between the float member and the bottom member when til the two are brought into juxtaposition thereby to define a passageway from the interior of the ram through the opening in the float member and said portion of the opening in the ram member to the interior of the cylinder; and means operatively associated with one member and having a part thereof in said passageway to close said passageway in response to the continued injection of air into said ram.

11. A lift for a vehicle or the like comprising: a hydraulic cylinder adapted to contain a quantity of hydraulic fluid and having its axis generally vertical; a hollow hydraulic ram in said cylinder, said ram having a bottom member with an opening therein; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of the ram above the normal level of hydraulic fluid therein, said tube being smaller than said opening whereby when air is injected into said ram through said tube hydraulic fluid will be forced from the interior of the ram through the portion of the opening between the bottom member and tube and into the cylinder to raise the ram; a float member inside the ram, surrounding the tube, buoyant with respect to said hydraulic fluid and movable vertically with respect to the tube, whereby the float member will normally, unless otherwise restrained, assume a position at the surface of the hydraulic fluid in the ram with a portion of the float member below the surface of the hydraulic fluid, said float member having an opening in said portion from the exterior thereof to the part of the float member about the tube adjacent the bottom of the float member; means between said members to form a seal between the float member and the bottom member when the two are brought into juxtaposition thereby to define a passageway from the interior of the ram through the opening in the float member and said portion of the opening in the ram member to the interior of the cylinder with a pressure differential existing between the two ends of the passageway, said means including a resilient bellows surrounding the tube and positioned between the members, said bellows having an annular portion normally spaced from the tube and resiliently forced against the tube by said pressure differential to close said passageway.

12. A lift for a vehicle or the like comprising: a hydraulic cylinder adapted to contain a quantity of hydraulic fluid and having its axis generally vertical; a hollow hydraulic ram in said cylinder, said rarn having an opening in the bottom thereof; a fixed air tube attached to said cylinder and extending upwardly through said opening into the interior of said ram above the normal level of hydraulic fluid therein, said tube being smaller than said opening to define an orifice thereabout; and a float having an opening therethrough from top to bottom, said opening being larger than said tube with the tube being received therethrough, said float being within the ram and adapted to float on the hydraulic fluid therein with a portion of'the float submerged, said portion having a duct therein from the exterior of the float to the opening therein, said float having a resilient bellows secured thereto and extending downwardly therefrom about the tube, said bellows including an annular portion normally spaced from the tube but adapted to collapse against the tube to form a seal thereabout.

13. A vehicle lift as set forth in claim 12, wherein said bellows has the configuration of an annular solid of revolution about the tube and includes means to prevent the expansion of the bellows both above and below said annular portion thereof.

14. A valve apparatus for a vehicle lift or the like having a hollow cylindrical ram mounted in a hydraulic cylinder adapted to contain a quantity of hydraulic fluid and with a cylindrical air tube extending from the cylinder vertically upwardly through an opening in the bottom of the ram and terminating in the interior of the ram above the normal level of hydraulic fluid therein,

1 l 1 2 said apparatus comprising: a float having an axial openeluding an annular portion normally spaced from the ing therethrough of a diameter only slightly larger than tube but adapted to collapse against the tube to form a the external diameter of said tube whereby said float may seal thereabout. be slipped over said tube in the ram with the tube through the opening in the float, said float being adapted to float 5 References Cited in the file of this Patent on the hydraulic fluid therein with a portion of the float UNITED STATES PATENTS submerged, said portion having a duet therein from the 2 402 265 Thompson June 18 1940 eAterior of the float to the openlng therein, said float 2,637,302 Harrison M y 1953 having a resilient bellows secured thereto and extending downwardly therefrom about the tube, said bellows in- 10 2970577 Sinclair 1961 

1. A LIFT FOR A VEHICLE OR THE LIKE COMPRISING: A HYDRAULIC CYLINDER HAVING ITS AXIS GENERALLY VERTICAL AND ADAPTED TO CONTAIN A QUANTITY OF HYDRAULIC FLUID; A HOLLOW HYDRAULIC RAM IN SAID CYLINDER, SAID RAM HAVING AN OPENING IN THE BOTTOM THEREOF; A FIXED AIR TUBE ATTACHED TO SAID CYLINDER AND EXTENDING UPWARDLY THROUGH SAID OPENING INTO THE INTERIOR OF SAID RAM ABOVE THE NORMAL LEVEL OF HYDRAULIC FLUID THEREIN, SAID TUBE BEING SMALLER THAN SAID OPENING TO DEFINE AN ORIFICE THEREABOUT; A FLOAT INSIDE SAID RAM, SURROUNDING SAID TUBE AND MOVABLE VERTICALLY WITH RESPECT TO SAID TUBE, SAID FLOAT HAVING MEANS ON THE BOTTOM THEREOF TO FORM A FLUID SEAL BETWEEN THE FLOAT AND THE BOTTOM OF SAID RAM ABOUT SAID ORIFICE WHEN SAID FLOAT AND BOTTOM ARE IN JUXTAPOSITION, SAID FLOAT BEING BUOYANT WITH RESPECT TO SAID HYDRAULIC FLUID; MEANS BETWEEN SAID FLOAT AND TUBE TO FORM A SEAL THEREBETWEEN WHEN SAID FLOAT AND BOTTOM ARE IN JUXTAPOSITION; AND MEANS TO LIMIT THE EXTENT OF UPWARD MOVEMENT OF THE FLOAT WITH RESPECT TO THE TUBE, THE LAST MEANS BEING VERTICALLY ADJUSTABLE WHEREBY THE HEIGHT TO WHICH THE FLOAT WILL RISE MAY BE VARIED. 